diff --git a/packages/app/pr/screenshots/session-perf-compaction-smoke.png b/packages/app/pr/screenshots/session-perf-compaction-smoke.png
new file mode 100644
index 000000000..b62458e83
Binary files /dev/null and b/packages/app/pr/screenshots/session-perf-compaction-smoke.png differ
diff --git a/packages/app/src/app/app.tsx b/packages/app/src/app/app.tsx
index a80297c2e..bfb0ac101 100644
--- a/packages/app/src/app/app.tsx
+++ b/packages/app/src/app/app.tsx
@@ -41,11 +41,13 @@ import { createClient, unwrap, waitForHealthy, type OpencodeAuth } from "./lib/o
 import {
   abortSession as abortSessionTyped,
   abortSessionSafe,
+  compactSession as compactSessionTyped,
   revertSession,
   unrevertSession,
   shellInSession,
   listCommands as listCommandsTyped,
 } from "./lib/opencode-session";
+import { clearPerfLogs, finishPerf, perfNow, recordPerfLog } from "./lib/perf-log";
 import {
   DEFAULT_MODEL,
   HIDE_TITLEBAR_PREF_KEY,
@@ -589,6 +591,11 @@ export default function App() {
   const [developerMode, setDeveloperMode] = createSignal(false);
   const [documentVisible, setDocumentVisible] = createSignal(true);
 
+  createEffect(() => {
+    if (developerMode()) return;
+    clearPerfLogs();
+  });
+
   const [selectedSessionId, setSelectedSessionId] = createSignal<string | null>(
     null
   );
@@ -847,6 +854,15 @@ export default function App() {
 
     const c = client();
     if (!c) return;
+
+    const compactShortcut = /^\/compact(?:\s+.*)?$/i.test(content);
+    const compactCommand = resolvedDraft.command?.name === "compact" || compactShortcut;
+    const commandName = compactCommand ? "compact" : (resolvedDraft.command?.name ?? null);
+    if (compactCommand && !selectedSessionId()) {
+      setError("Select a session with messages before running /compact.");
+      return;
+    }
+
     let sessionID = selectedSessionId();
     if (!sessionID) {
       await createSessionAndOpen();
@@ -859,8 +875,24 @@ export default function App() {
     setBusyStartedAt(Date.now());
     setError(null);
 
+    const perfEnabled = developerMode();
+    const startedAt = perfNow();
+    const visible = messages();
+    const visibleParts = visible.reduce((total, message) => total + message.parts.length, 0);
+    recordPerfLog(perfEnabled, "session.prompt", "start", {
+      sessionID,
+      mode: resolvedDraft.mode,
+      command: commandName,
+      charCount: content.length,
+      attachmentCount: resolvedDraft.attachments.length,
+      messageCount: visible.length,
+      partCount: visibleParts,
+    });
+
     try {
-      setLastPromptSent(content);
+      if (!compactCommand) {
+        setLastPromptSent(content);
+      }
       setPrompt("");
 
       const model = selectedSessionModel();
@@ -869,7 +901,22 @@ export default function App() {
 
       if (resolvedDraft.mode === "shell") {
         await shellInSession(c, sessionID, content);
-      } else if (resolvedDraft.command) {
+      } else if (resolvedDraft.command || compactCommand) {
+        if (compactCommand) {
+          await compactCurrentSession(sessionID);
+          finishPerf(perfEnabled, "session.prompt", "done", startedAt, {
+            sessionID,
+            mode: resolvedDraft.mode,
+            command: commandName,
+          });
+          return;
+        }
+
+        const command = resolvedDraft.command;
+        if (!command) {
+          throw new Error("Command was not resolved.");
+        }
+
         // Slash command: route through session.command() API
         const selected = selectedSessionModel();
         const modelString = `${selected.providerID}/${selected.modelID}`;
@@ -879,8 +926,8 @@ export default function App() {
         unwrap(
           await c.session.command({
             sessionID,
-            command: resolvedDraft.command.name,
-            arguments: resolvedDraft.command.arguments,
+            command: command.name,
+            arguments: command.arguments,
             agent: agent ?? undefined,
             model: modelString,
             variant: modelVariant() ?? undefined,
@@ -910,7 +957,19 @@ export default function App() {
           return copy;
         });
       }
+
+      finishPerf(perfEnabled, "session.prompt", "done", startedAt, {
+        sessionID,
+        mode: resolvedDraft.mode,
+        command: commandName,
+      });
     } catch (e) {
+      finishPerf(perfEnabled, "session.prompt", "error", startedAt, {
+        sessionID,
+        mode: resolvedDraft.mode,
+        command: commandName,
+        error: e instanceof Error ? e.message : safeStringify(e),
+      });
       const message = e instanceof Error ? e.message : safeStringify(e);
       setError(addOpencodeCacheHint(message));
     } finally {
@@ -942,6 +1001,52 @@ export default function App() {
     });
   }
 
+  async function compactCurrentSession(sessionIdOverride?: string) {
+    const c = client();
+    if (!c) {
+      throw new Error("Not connected to a server");
+    }
+
+    const sessionID = (sessionIdOverride ?? selectedSessionId() ?? "").trim();
+    if (!sessionID) {
+      throw new Error("Select a session before compacting.");
+    }
+
+    const visible = messages();
+    if (!visible.length) {
+      throw new Error("Nothing to compact yet.");
+    }
+
+    const model = selectedSessionModel();
+    const startedAt = perfNow();
+    const modelLabel = `${model.providerID}/${model.modelID}`;
+    recordPerfLog(developerMode(), "session.compact", "start", {
+      sessionID,
+      messageCount: visible.length,
+      model: modelLabel,
+      variant: modelVariant() ?? null,
+    });
+
+    try {
+      await compactSessionTyped(c, sessionID, model, {
+        directory: workspaceProjectDir().trim() || undefined,
+      });
+      finishPerf(developerMode(), "session.compact", "done", startedAt, {
+        sessionID,
+        messageCount: visible.length,
+        model: modelLabel,
+      });
+    } catch (error) {
+      finishPerf(developerMode(), "session.compact", "error", startedAt, {
+        sessionID,
+        messageCount: visible.length,
+        model: modelLabel,
+        error: error instanceof Error ? error.message : safeStringify(error),
+      });
+      throw error;
+    }
+  }
+
   const messageIdFromInfo = (message: MessageWithParts) => {
     const id = (message.info as { id?: string | number }).id;
     if (typeof id === "string") return id;
@@ -1144,10 +1249,21 @@ export default function App() {
     return list.filter((agent) => !agent.hidden && agent.mode !== "subagent");
   }
 
+  const BUILTIN_COMPACT_COMMAND = {
+    id: "builtin:compact",
+    name: "compact",
+    description: "Summarize this session to reduce context size.",
+    source: "command" as const,
+  };
+
   async function listCommands(): Promise<{ id: string; name: string; description?: string; source?: "command" | "mcp" | "skill" }[]> {
     const c = client();
     if (!c) return [];
-    return listCommandsTyped(c, workspaceStore.activeWorkspaceRoot().trim() || undefined);
+    const list = await listCommandsTyped(c, workspaceStore.activeWorkspaceRoot().trim() || undefined);
+    if (list.some((entry) => entry.name === "compact")) {
+      return list;
+    }
+    return [BUILTIN_COMPACT_COMMAND, ...list];
   }
 
   function setSessionAgent(sessionID: string, agent: string | null) {
@@ -3208,13 +3324,19 @@ export default function App() {
   }
 
   async function connectMcp(entry: (typeof MCP_QUICK_CONNECT)[number]) {
-    console.log("[connectMcp] called with entry:", entry);
-
+    const startedAt = perfNow();
     const isRemoteWorkspace =
       workspaceStore.activeWorkspaceDisplay().workspaceType === "remote" ||
       (!isTauriRuntime() && openworkServerStatus() === "connected");
     const projectDir = workspaceProjectDir().trim();
-    console.log("[connectMcp] projectDir:", projectDir);
+    const entryType = entry.type ?? "remote";
+
+    recordPerfLog(developerMode(), "mcp.connect", "start", {
+      name: entry.name,
+      type: entryType,
+      workspaceType: isRemoteWorkspace ? "remote" : "local",
+      projectDir: projectDir || null,
+    });
 
     const openworkClient = openworkServerClient();
     let openworkWorkspaceId = openworkServerWorkspaceId();
@@ -3238,26 +3360,30 @@ export default function App() {
       openworkCapabilities?.mcp?.write;
 
     if (isRemoteWorkspace && !canUseOpenworkServer) {
-      console.log("[connectMcp] ❌ openwork server unavailable");
       setMcpStatus("OpenWork server unavailable. MCP config is read-only.");
+      finishPerf(developerMode(), "mcp.connect", "blocked", startedAt, {
+        reason: "openwork-server-unavailable",
+      });
       return;
     }
 
     if (!canUseOpenworkServer && !isTauriRuntime()) {
-      console.log("[connectMcp] ❌ not Tauri runtime");
       setMcpStatus(t("mcp.desktop_required", currentLocale()));
+      finishPerf(developerMode(), "mcp.connect", "blocked", startedAt, {
+        reason: "desktop-required",
+      });
       return;
     }
-    console.log("[connectMcp] ✓ runtime ready");
 
     if (!isRemoteWorkspace && !projectDir) {
-      console.log("[connectMcp] ❌ no projectDir");
       setMcpStatus(t("mcp.pick_workspace_first", currentLocale()));
+      finishPerf(developerMode(), "mcp.connect", "blocked", startedAt, {
+        reason: "missing-workspace",
+      });
       return;
     }
 
     let activeClient = client();
-    console.log("[connectMcp] activeClient:", activeClient ? "exists" : "null");
     if (!activeClient) {
       const openworkBaseUrl = openworkServerBaseUrl().trim();
       const auth = openworkServerAuth();
@@ -3268,8 +3394,10 @@ export default function App() {
       }
     }
     if (!activeClient) {
-      console.log("[connectMcp] ❌ no activeClient");
       setMcpStatus(t("mcp.connect_server_first", currentLocale()));
+      finishPerf(developerMode(), "mcp.connect", "blocked", startedAt, {
+        reason: "no-active-client",
+      });
       return;
     }
 
@@ -3288,24 +3416,24 @@ export default function App() {
       }
     }
     if (!resolvedProjectDir) {
-      console.log("[connectMcp] ❌ no projectDir after lookup");
       setMcpStatus(t("mcp.pick_workspace_first", currentLocale()));
+      finishPerf(developerMode(), "mcp.connect", "blocked", startedAt, {
+        reason: "missing-workspace-after-discovery",
+      });
       return;
     }
 
     const slug = entry.name.toLowerCase().replace(/[^a-z0-9]+/g, "-");
-    const entryType = entry.type ?? "remote";
-    console.log("[connectMcp] slug:", slug);
 
     try {
       setMcpStatus(null);
       setMcpConnectingName(entry.name);
-      console.log("[connectMcp] connecting name set to:", entry.name);
 
       const mcpEntryConfig: Record<string, unknown> = {
         type: entryType,
         enabled: true,
       };
+
       if (entryType === "remote") {
         if (!entry.url) {
           throw new Error("Missing MCP URL.");
@@ -3315,62 +3443,52 @@ export default function App() {
           mcpEntryConfig["oauth"] = {};
         }
       }
+
       if (entryType === "local") {
         if (!entry.command?.length) {
           throw new Error("Missing MCP command.");
         }
         mcpEntryConfig["command"] = entry.command;
       }
+
       if (canUseOpenworkServer && openworkClient && openworkWorkspaceId) {
         await openworkClient.addMcp(openworkWorkspaceId, {
           name: slug,
           config: mcpEntryConfig,
         });
-        console.log("[connectMcp] added MCP via OpenWork server");
       } else {
-        // Step 1: Read existing opencode.json config
-        console.log("[connectMcp] reading opencode config for projectDir:", projectDir);
         const configFile = await readOpencodeConfig("project", resolvedProjectDir);
-        console.log("[connectMcp] config file result:", configFile);
 
-        // Step 2: Parse and merge the MCP entry into the config
         let existingConfig: Record<string, unknown> = {};
         if (configFile.exists && configFile.content?.trim()) {
           try {
             existingConfig = parse(configFile.content) ?? {};
-            console.log("[connectMcp] parsed existing config:", existingConfig);
           } catch (parseErr) {
-            console.warn("[connectMcp] failed to parse existing config, starting fresh:", parseErr);
+            recordPerfLog(developerMode(), "mcp.connect", "config-parse-failed", {
+              error: parseErr instanceof Error ? parseErr.message : String(parseErr),
+            });
             existingConfig = {};
           }
         }
 
-        // Ensure base structure
         if (!existingConfig["$schema"]) {
           existingConfig["$schema"] = "https://opencode.ai/config.json";
         }
 
-        // Ensure mcp object exists
         const mcpSection = (existingConfig["mcp"] as Record<string, unknown>) ?? {};
         existingConfig["mcp"] = mcpSection;
-
-        // Add the new MCP server entry
         mcpSection[slug] = mcpEntryConfig;
-        console.log("[connectMcp] merged MCP config:", existingConfig);
 
-        // Step 3: Write the updated config back
         const writeResult = await writeOpencodeConfig(
           "project",
           resolvedProjectDir,
           `${JSON.stringify(existingConfig, null, 2)}\n`
         );
-        console.log("[connectMcp] writeOpencodeConfig result:", writeResult);
         if (!writeResult.ok) {
           throw new Error(writeResult.stderr || writeResult.stdout || "Failed to write opencode.json");
         }
       }
 
-      // Step 4: Call SDK mcp.add to update runtime state
       const mcpAddConfig =
         entryType === "remote"
           ? {
@@ -3385,25 +3503,18 @@ export default function App() {
             enabled: true,
           };
 
-      const mcpAddPayload = {
-        directory: resolvedProjectDir,
-        name: slug,
-        config: mcpAddConfig,
-      };
-      console.log("[connectMcp] calling activeClient.mcp.add with:", mcpAddPayload);
-
-      const rawResult = await activeClient.mcp.add(mcpAddPayload);
-      console.log("[connectMcp] mcp.add raw result:", rawResult);
-
-      const status = unwrap(rawResult);
-      console.log("[connectMcp] mcp.add unwrapped status:", status);
+      const status = unwrap(
+        await activeClient.mcp.add({
+          directory: resolvedProjectDir,
+          name: slug,
+          config: mcpAddConfig,
+        }),
+      );
 
       setMcpStatuses(status as McpStatusMap);
       await refreshMcpServers();
 
-      // Step 5: If OAuth, open the auth modal (modal handles the auth flow)
       if (entry.oauth) {
-        console.log("[connectMcp] entry has OAuth, opening auth modal for:", entry.name);
         setMcpAuthEntry(entry);
         setMcpAuthModalOpen(true);
       } else {
@@ -3411,13 +3522,20 @@ export default function App() {
       }
 
       await refreshMcpServers();
-      console.log("[connectMcp] ✓ done");
+      finishPerf(developerMode(), "mcp.connect", "done", startedAt, {
+        name: entry.name,
+        type: entryType,
+        slug,
+      });
     } catch (e) {
-      console.error("[connectMcp] ❌ error:", e);
       setMcpStatus(e instanceof Error ? e.message : t("mcp.connect_failed", currentLocale()));
+      finishPerf(developerMode(), "mcp.connect", "error", startedAt, {
+        name: entry.name,
+        type: entryType,
+        error: e instanceof Error ? e.message : safeStringify(e),
+      });
     } finally {
       setMcpConnectingName(null);
-      console.log("[connectMcp] finally block, connecting name cleared");
     }
   }
 
@@ -3555,35 +3673,46 @@ export default function App() {
   }
 
   async function createSessionAndOpen() {
-    console.log("[DEBUG] createSessionAndOpen");
-    console.log("[DEBUG] current baseUrl:", baseUrl());
-    console.log("[DEBUG] engine info:", engine());
-    console.log("[DEBUG] creating session");
     const c = client();
     if (!c) {
-      console.log("[DEBUG] no client available!");
       return;
     }
 
+    const perfEnabled = developerMode();
+    const startedAt = perfNow();
+    const runId = (() => {
+      const key = "__openwork_create_session_run__";
+      const w = window as typeof window & { [key]?: number };
+      w[key] = (w[key] ?? 0) + 1;
+      return w[key];
+    })();
+
+    const mark = (event: string, payload?: Record<string, unknown>) => {
+      const elapsed = Math.round((perfNow() - startedAt) * 100) / 100;
+      recordPerfLog(perfEnabled, "session.create", event, {
+        runId,
+        elapsedMs: elapsed,
+        ...(payload ?? {}),
+      });
+    };
+
+    mark("start", {
+      baseUrl: baseUrl(),
+      workspace: workspaceStore.activeWorkspaceRoot().trim() || null,
+    });
+
     // Abort any in-flight refresh operations to free up connection resources
-    console.log("[DEBUG] aborting in-flight refreshes");
     abortRefreshes();
 
     // Small delay to allow pending requests to settle
     await new Promise((resolve) => setTimeout(resolve, 50));
 
-    console.log("[DEBUG] client found");
     setBusy(true);
-    console.log("[DEBUG] busy set");
     setBusyLabel("status.creating_task");
-    console.log("[DEBUG] busy label set");
     setBusyStartedAt(Date.now());
-    console.log("[DEBUG] busy started at set");
     setError(null);
-    console.log("[DEBUG] error set");
     setCreatingSession(true);
 
-    console.log("[DEBUG] with timeout defined");
     const withTimeout = async <T,>(
       promise: Promise<T>,
       ms: number,
@@ -3605,55 +3734,39 @@ export default function App() {
       }
     };
 
-    const runId = (() => {
-      const key = "__openwork_create_session_run__";
-      const w = window as typeof window & { [key]?: number };
-      w[key] = (w[key] ?? 0) + 1;
-      return w[key];
-    })();
-
-    const mark = (() => {
-      const start = Date.now();
-      return (label: string, payload?: unknown) => {
-        const elapsedMs = Date.now() - start;
-        if (payload === undefined) {
-          console.log(`[run ${runId}] ${label} (+${elapsedMs}ms)`);
-        } else {
-          console.log(`[run ${runId}] ${label} (+${elapsedMs}ms)`, payload);
-        }
-      };
-    })();
-
     try {
       // Quick health check to detect stale connection
-      mark("checking health");
+      mark("health:start");
       try {
-        const healthResult = await withTimeout(c.global.health(), 3_000, "health");
-        mark("health ok", healthResult);
+        await withTimeout(c.global.health(), 3_000, "health");
+        mark("health:ok");
       } catch (healthErr) {
-        mark("health FAILED", healthErr);
+        mark("health:error", {
+          error: healthErr instanceof Error ? healthErr.message : safeStringify(healthErr),
+        });
         throw new Error(t("app.connection_lost", currentLocale()));
       }
 
       let rawResult: Awaited<ReturnType<typeof c.session.create>>;
       try {
-        mark("creating session");
+        mark("session:create:start");
         rawResult = await c.session.create({
           directory: workspaceStore.activeWorkspaceRoot().trim(),
         });
-        mark("session created");
+        mark("session:create:ok");
       } catch (createErr) {
-        mark("session create error", createErr);
+        mark("session:create:error", {
+          error: createErr instanceof Error ? createErr.message : safeStringify(createErr),
+        });
         throw createErr;
       }
-      mark("raw result received");
+
       const session = unwrap(rawResult);
-      mark("session unwrapped");
       // Immediately select and show the new session before background list refresh.
       setBusyLabel("status.loading_session");
+      mark("session:select:start", { sessionID: session.id });
       await selectSession(session.id);
-      mark("selectSession (immediate)");
-      mark("session selected");
+      mark("session:select:ok", { sessionID: session.id });
 
       // Inject the new session into the reactive sessions() store so
       // the createEffect bridge (sessions → sidebar) will always include it,
@@ -3662,7 +3775,6 @@ export default function App() {
       if (!currentStoreSessions.some((s) => s.id === session.id)) {
         setSessions([session, ...currentStoreSessions]);
       }
-      mark("session injected into store");
 
       const newItem: SidebarSessionItem = {
         id: session.id,
@@ -3683,9 +3795,7 @@ export default function App() {
           [wsId]: "ready",
         }));
       }
-      mark("sidebar injected");
 
-      mark("view set to session");
       // setSessionViewLockUntil(Date.now() + 1200);
       goToSession(session.id);
 
@@ -3695,10 +3805,16 @@ export default function App() {
       // race with the store injection — the server may not have indexed the
       // session yet, so reconcile() would wipe it from the store, causing
       // the sidebar to flash and the route guard to bounce back.
-      mark("done (SSE will sync)");
+      finishPerf(perfEnabled, "session.create", "done", startedAt, {
+        runId,
+        sessionID: session.id,
+      });
       return session.id;
     } catch (e) {
-      mark("error caught", e);
+      finishPerf(perfEnabled, "session.create", "error", startedAt, {
+        runId,
+        error: e instanceof Error ? e.message : safeStringify(e),
+      });
       const message = e instanceof Error ? e.message : t("app.unknown_error", currentLocale());
       setError(addOpencodeCacheHint(message));
       return undefined;
@@ -4771,6 +4887,7 @@ export default function App() {
     sessionRevertMessageId: selectedSession()?.revert?.messageID ?? null,
     undoLastUserMessage: undoLastUserMessage,
     redoLastUserMessage: redoLastUserMessage,
+    compactSession: compactCurrentSession,
     lastPromptSent: lastPromptSent(),
     retryLastPrompt: retryLastPrompt,
     newTaskDisabled: newTaskDisabled(),
diff --git a/packages/app/src/app/components/session/message-list.tsx b/packages/app/src/app/components/session/message-list.tsx
index 2caa1af7b..53a22aeee 100644
--- a/packages/app/src/app/components/session/message-list.tsx
+++ b/packages/app/src/app/components/session/message-list.tsx
@@ -6,6 +6,7 @@ import { Check, ChevronDown, ChevronRight, Copy, Eye, File, FileEdit, FolderSear
 import type { MessageGroup, MessageWithParts } from "../../types";
 import { groupMessageParts, summarizeStep } from "../../utils";
 import PartView from "../part-view";
+import { perfNow, recordPerfLog } from "../../lib/perf-log";
 
 export type MessageListProps = {
   messages: MessageWithParts[];
@@ -195,6 +196,7 @@ export default function MessageList(props: MessageListProps) {
     });
 
   const messageBlocks = createMemo<MessageBlockItem[]>(() => {
+    const startedAt = perfNow();
     const blocks: MessageBlockItem[] = [];
 
     for (const message of props.messages) {
@@ -237,6 +239,15 @@ export default function MessageList(props: MessageListProps) {
       });
     }
 
+    const elapsedMs = Math.round((perfNow() - startedAt) * 100) / 100;
+    if (props.developerMode && (elapsedMs >= 8 || props.messages.length >= 120)) {
+      recordPerfLog(true, "session.render", "message-blocks", {
+        messageCount: props.messages.length,
+        blockCount: blocks.length,
+        ms: elapsedMs,
+      });
+    }
+
     return blocks;
   });
 
diff --git a/packages/app/src/app/context/session.ts b/packages/app/src/app/context/session.ts
index 2b06ebe6f..d7052bd89 100644
--- a/packages/app/src/app/context/session.ts
+++ b/packages/app/src/app/context/session.ts
@@ -25,6 +25,7 @@ import {
   safeStringify,
 } from "../utils";
 import { unwrap } from "../lib/opencode";
+import { finishPerf, perfNow, recordPerfLog } from "../lib/perf-log";
 
 export type SessionModelState = {
   overrides: Record<string, ModelRef>;
@@ -500,10 +501,17 @@ export function createSessionStore(options: {
       w[key] = (w[key] ?? 0) + 1;
       return w[key];
     })();
-    const mark = (() => {
-      const start = Date.now();
-      return (label: string) => console.log(`[selectSession run ${runId}] ${label} (+${Date.now() - start}ms)`);
-    })();
+    const perfEnabled = options.developerMode();
+    const startedAt = perfNow();
+    const mark = (event: string, payload?: Record<string, unknown>) => {
+      const elapsedMs = Math.round((perfNow() - startedAt) * 100) / 100;
+      recordPerfLog(perfEnabled, "session.select", event, {
+        runId,
+        sessionID,
+        elapsedMs,
+        ...(payload ?? {}),
+      });
+    };
 
     mark("start");
     options.setSelectedSessionId(sessionID);
@@ -513,8 +521,10 @@ export function createSessionStore(options: {
     try {
       await withTimeout(c.global.health(), 3000, "health");
       mark("health ok");
-    } catch {
-      mark("health FAILED");
+    } catch (error) {
+      mark("health FAILED", {
+        error: error instanceof Error ? error.message : safeStringify(error),
+      });
       throw new Error("Server connection lost. Please reload.");
     }
 
@@ -555,8 +565,10 @@ export function createSessionStore(options: {
         return;
       }
       setStore("todos", sessionID, list);
-    } catch {
-      mark("session.todo failed/timeout");
+    } catch (error) {
+      mark("session.todo failed/timeout", {
+        error: error instanceof Error ? error.message : safeStringify(error),
+      });
       setStore("todos", sessionID, []);
     }
 
@@ -568,11 +580,18 @@ export function createSessionStore(options: {
         mark("aborting: selection changed before permissions applied");
         return;
       }
-    } catch {
-      mark("permission.list failed/timeout");
+    } catch (error) {
+      mark("permission.list failed/timeout", {
+        error: error instanceof Error ? error.message : safeStringify(error),
+      });
     }
 
-    mark("selectSession complete");
+    finishPerf(perfEnabled, "session.select", "complete", startedAt, {
+      runId,
+      sessionID,
+      messageCount: msgs.length,
+      todoCount: (store.todos[sessionID] ?? []).length,
+    });
   }
 
   async function respondPermission(requestID: string, reply: "once" | "always" | "reject") {
@@ -930,12 +949,26 @@ export function createSessionStore(options: {
       if (eventsToApply.length === 0) return;
 
       last = Date.now();
+      const startedAt = perfNow();
+      let applied = 0;
       batch(() => {
         for (const event of eventsToApply) {
           if (!event) continue;
+          applied += 1;
           void applyEvent(event);
         }
       });
+
+      const elapsedMs = Math.round((perfNow() - startedAt) * 100) / 100;
+      const dropped = eventsToApply.length - applied;
+      if (sessionDebugEnabled() && (elapsedMs >= 12 || applied >= 40 || dropped >= 20)) {
+        recordPerfLog(true, "session.sse", "flush", {
+          queued: eventsToApply.length,
+          applied,
+          dropped,
+          ms: elapsedMs,
+        });
+      }
     };
 
     const schedule = () => {
@@ -951,6 +984,7 @@ export function createSessionStore(options: {
 
         // Reset reconnect counter on successful connection
         reconnectAttempt = 0;
+        recordPerfLog(sessionDebugEnabled(), "session.sse", "connected");
 
         for await (const raw of sub.stream) {
           if (cancelled) break;
@@ -978,6 +1012,7 @@ export function createSessionStore(options: {
         // Stream ended normally - attempt reconnect unless cancelled
         if (!cancelled) {
           options.setSseConnected(false);
+          recordPerfLog(sessionDebugEnabled(), "session.sse", "stream-ended");
           scheduleReconnect(controller);
         }
       } catch (e) {
@@ -988,6 +1023,9 @@ export function createSessionStore(options: {
 
         // Mark SSE as disconnected and schedule reconnect
         options.setSseConnected(false);
+        recordPerfLog(sessionDebugEnabled(), "session.sse", "stream-error", {
+          error: message,
+        });
         scheduleReconnect(controller);
       }
     };
@@ -999,6 +1037,10 @@ export function createSessionStore(options: {
       // Exponential backoff: 1s, 2s, 4s, 8s, 16s, max 30s
       reconnectAttempt++;
       const delay = Math.min(1000 * Math.pow(2, reconnectAttempt - 1), 30000);
+      recordPerfLog(sessionDebugEnabled(), "session.sse", "reconnect-scheduled", {
+        attempt: reconnectAttempt,
+        delayMs: delay,
+      });
 
       reconnectTimer = setTimeout(() => {
         if (cancelled) return;
diff --git a/packages/app/src/app/lib/opencode-session.ts b/packages/app/src/app/lib/opencode-session.ts
index c03e29299..713638e8f 100644
--- a/packages/app/src/app/lib/opencode-session.ts
+++ b/packages/app/src/app/lib/opencode-session.ts
@@ -8,7 +8,7 @@
  * (e.g. `shellAsync`) that may not be present in older SDK versions.
  */
 import type { Session } from "@opencode-ai/sdk/v2/client";
-import type { Client } from "../types";
+import type { Client, ModelRef } from "../types";
 import { unwrap } from "./opencode";
 
 // ---------------------------------------------------------------------------
@@ -54,6 +54,45 @@ export async function unrevertSession(
   return unwrap(await client.session.unrevert({ sessionID })) as Session;
 }
 
+/**
+ * Compact/summarize a long session to reduce context size.
+ * Uses `session.summarize` when available and falls back to `/compact` command.
+ */
+export async function compactSession(
+  client: Client,
+  sessionID: string,
+  model: ModelRef,
+  options?: { directory?: string },
+): Promise<void> {
+  const session = client.session as { summarize?: (input: {
+    sessionID: string;
+    directory?: string;
+    providerID: string;
+    modelID: string;
+  }) => Promise<unknown> };
+
+  if (typeof session.summarize === "function") {
+    const result = await session.summarize({
+      sessionID,
+      directory: options?.directory,
+      providerID: model.providerID,
+      modelID: model.modelID,
+    });
+    assertNoClientError(result);
+    return;
+  }
+
+  const modelString = `${model.providerID}/${model.modelID}`;
+  const result = await client.session.command({
+    sessionID,
+    command: "compact",
+    arguments: "",
+    model: modelString,
+    directory: options?.directory,
+  });
+  assertNoClientError(result);
+}
+
 // ---------------------------------------------------------------------------
 // Shell execution
 // ---------------------------------------------------------------------------
diff --git a/packages/app/src/app/lib/perf-log.ts b/packages/app/src/app/lib/perf-log.ts
new file mode 100644
index 000000000..8f6b97c1f
--- /dev/null
+++ b/packages/app/src/app/lib/perf-log.ts
@@ -0,0 +1,91 @@
+export type PerfLogRecord = {
+  id: number;
+  at: string;
+  ts: number;
+  scope: string;
+  event: string;
+  payload?: Record<string, unknown>;
+};
+
+type PerfRoot = typeof globalThis & {
+  __openworkPerfSeq?: number;
+  __openworkPerfLogs?: PerfLogRecord[];
+};
+
+const PERF_LOG_LIMIT = 500;
+
+export const perfNow = () => {
+  if (typeof performance !== "undefined" && typeof performance.now === "function") {
+    return performance.now();
+  }
+  return Date.now();
+};
+
+const round = (value: number) => Math.round(value * 100) / 100;
+
+export const recordPerfLog = (
+  enabled: boolean,
+  scope: string,
+  event: string,
+  payload?: Record<string, unknown>,
+) => {
+  if (!enabled) return;
+
+  const root = globalThis as PerfRoot;
+  const id = (root.__openworkPerfSeq ?? 0) + 1;
+  root.__openworkPerfSeq = id;
+
+  const entry: PerfLogRecord = {
+    id,
+    at: new Date().toISOString(),
+    ts: Date.now(),
+    scope,
+    event,
+    payload,
+  };
+
+  const logs = root.__openworkPerfLogs ?? [];
+  logs.push(entry);
+  if (logs.length > PERF_LOG_LIMIT) {
+    logs.splice(0, logs.length - PERF_LOG_LIMIT);
+  }
+  root.__openworkPerfLogs = logs;
+
+  try {
+    if (payload === undefined) {
+      console.log(`[OWPERF] ${scope}:${event}`);
+      return;
+    }
+    console.log(`[OWPERF] ${scope}:${event}`, payload);
+  } catch {
+    // ignore
+  }
+};
+
+export const readPerfLogs = (limit = 120) => {
+  const root = globalThis as PerfRoot;
+  const logs = root.__openworkPerfLogs ?? [];
+  if (limit <= 0) return [];
+  if (logs.length <= limit) return logs.slice();
+  return logs.slice(logs.length - limit);
+};
+
+export const clearPerfLogs = () => {
+  const root = globalThis as PerfRoot;
+  root.__openworkPerfLogs = [];
+  root.__openworkPerfSeq = 0;
+};
+
+export const finishPerf = (
+  enabled: boolean,
+  scope: string,
+  event: string,
+  startedAt: number,
+  payload?: Record<string, unknown>,
+) => {
+  if (!enabled) return;
+  recordPerfLog(enabled, scope, event, {
+    ...(payload ?? {}),
+    ms: round(perfNow() - startedAt),
+  });
+};
diff --git a/packages/app/src/app/pages/config.tsx b/packages/app/src/app/pages/config.tsx
index 8fc64d034..28b88b206 100644
--- a/packages/app/src/app/pages/config.tsx
+++ b/packages/app/src/app/pages/config.tsx
@@ -1,6 +1,7 @@
 import { Show, createEffect, createMemo, createSignal, onCleanup } from "solid-js";
 
 import { isTauriRuntime } from "../utils";
+import { readPerfLogs } from "../lib/perf-log";
 
 import Button from "../components/button";
 import TextInput from "../components/text-input";
@@ -140,6 +141,7 @@ export default function ConfigView(props: ConfigViewProps) {
     const urlOverride = props.openworkServerSettings.urlOverride?.trim() ?? "";
     const token = props.openworkServerSettings.token?.trim() ?? "";
     const host = hostInfo();
+    const perfLogs = props.developerMode ? readPerfLogs(80) : [];
     return {
       capturedAt: new Date().toISOString(),
       runtime: {
@@ -178,6 +180,10 @@ export default function ConfigView(props: ConfigViewProps) {
         hostConnectUrl: hostConnectUrl() || null,
         hostConnectUrlUsesMdns: hostConnectUrlUsesMdns(),
       },
+      performance: {
+        retainedEntries: perfLogs.length,
+        recent: perfLogs,
+      },
     };
   });
 
diff --git a/packages/app/src/app/pages/session.tsx b/packages/app/src/app/pages/session.tsx
index c808efb45..75e494d61 100644
--- a/packages/app/src/app/pages/session.tsx
+++ b/packages/app/src/app/pages/session.tsx
@@ -69,6 +69,7 @@ import {
   normalizeDirectoryPath,
   parseTemplateFrontmatter,
 } from "../utils";
+import { finishPerf, perfNow, recordPerfLog } from "../lib/perf-log";
 
 import browserSetupTemplate from "../data/commands/browser-setup.md?raw";
 import soulSetupTemplate from "../data/commands/give-me-a-soul.md?raw";
@@ -134,6 +135,7 @@ export type SessionViewProps = {
   sessionRevertMessageId: string | null;
   undoLastUserMessage: () => Promise<void>;
   redoLastUserMessage: () => Promise<void>;
+  compactSession: () => Promise<void>;
   lastPromptSent: string;
   retryLastPrompt: () => void;
   newTaskDisabled: boolean;
@@ -223,7 +225,10 @@ const SOUL_SETUP_TEMPLATE = (() => {
 })();
 
 const INITIAL_MESSAGE_WINDOW = 140;
+const INITIAL_PART_WINDOW = 700;
 const MESSAGE_WINDOW_LOAD_CHUNK = 120;
+const MAX_SEARCH_MESSAGE_CHARS = 4_000;
+const MAX_SEARCH_HITS = 2_000;
 
 export default function SessionView(props: SessionViewProps) {
   let messagesEndEl: HTMLDivElement | undefined;
@@ -250,8 +255,9 @@ export default function SessionView(props: SessionViewProps) {
   const [scrollOnNextUpdate, setScrollOnNextUpdate] = createSignal(false);
   const [searchOpen, setSearchOpen] = createSignal(false);
   const [searchQuery, setSearchQuery] = createSignal("");
+  const [searchQueryDebounced, setSearchQueryDebounced] = createSignal("");
   const [activeSearchHitIndex, setActiveSearchHitIndex] = createSignal(0);
-  const [historyActionBusy, setHistoryActionBusy] = createSignal<"undo" | "redo" | null>(null);
+  const [historyActionBusy, setHistoryActionBusy] = createSignal<"undo" | "redo" | "compact" | null>(null);
   const [messageWindowStart, setMessageWindowStart] = createSignal(0);
   const [messageWindowSessionId, setMessageWindowSessionId] = createSignal<string | null>(null);
   const [messageWindowExpanded, setMessageWindowExpanded] = createSignal(false);
@@ -297,39 +303,68 @@ export default function SessionView(props: SessionViewProps) {
 
   const messageTextForSearch = (message: MessageWithParts) => {
     const chunks: string[] = [];
+    let used = 0;
+    const push = (value: string) => {
+      const next = value.trim();
+      if (!next) return;
+      if (used >= MAX_SEARCH_MESSAGE_CHARS) return;
+      const remaining = MAX_SEARCH_MESSAGE_CHARS - used;
+      if (next.length > remaining) {
+        chunks.push(next.slice(0, Math.max(0, remaining)));
+        used = MAX_SEARCH_MESSAGE_CHARS;
+        return;
+      }
+      chunks.push(next);
+      used += next.length;
+    };
+
     for (const part of message.parts) {
       if (part.type === "text") {
         const text = (part as { text?: string }).text ?? "";
-        if (text) chunks.push(text);
+        push(text);
         continue;
       }
       if (part.type === "agent") {
         const name = (part as { name?: string }).name ?? "";
-        if (name) chunks.push(`@${name}`);
+        push(name ? `@${name}` : "");
         continue;
       }
       if (part.type === "file") {
         const file = part as { label?: string; path?: string; filename?: string };
         const label = file.label ?? file.path ?? file.filename ?? "";
-        if (label) chunks.push(label);
+        push(label);
         continue;
       }
       if (part.type === "tool") {
         const state = (part as { state?: { title?: string; output?: string; error?: string } }).state;
-        if (state?.title) chunks.push(state.title);
-        if (state?.output) chunks.push(state.output);
-        if (state?.error) chunks.push(state.error);
+        push(state?.title ?? "");
+        push(state?.output ?? "");
+        push(state?.error ?? "");
       }
     }
     return chunks.join("\n");
   };
 
+  createEffect(() => {
+    const value = searchQuery();
+    if (typeof window === "undefined") {
+      setSearchQueryDebounced(value);
+      return;
+    }
+    const id = window.setTimeout(() => setSearchQueryDebounced(value), 90);
+    onCleanup(() => window.clearTimeout(id));
+  });
+
   const searchHits = createMemo<SearchHit[]>(() => {
-    const query = searchQuery().trim().toLowerCase();
+    if (!searchOpen()) return [];
+    const query = searchQueryDebounced().trim().toLowerCase();
     if (!query) return [];
 
+    const startedAt = perfNow();
     const hits: SearchHit[] = [];
-    for (const message of props.messages) {
+    let capped = false;
+
+    outer: for (const message of props.messages) {
       const messageId = messageIdFromInfo(message);
       if (!messageId) continue;
       const haystack = messageTextForSearch(message).toLowerCase();
@@ -337,9 +372,25 @@ export default function SessionView(props: SessionViewProps) {
       let index = haystack.indexOf(query);
       while (index !== -1) {
         hits.push({ messageId });
+        if (hits.length >= MAX_SEARCH_HITS) {
+          capped = true;
+          break outer;
+        }
         index = haystack.indexOf(query, index + Math.max(1, query.length));
       }
     }
+
+    const elapsedMs = Math.round((perfNow() - startedAt) * 100) / 100;
+    if (props.developerMode && (elapsedMs >= 8 || capped)) {
+      recordPerfLog(true, "session.search", "scan", {
+        queryLength: query.length,
+        messageCount: props.messages.length,
+        hitCount: hits.length,
+        capped,
+        ms: elapsedMs,
+      });
+    }
+
     return hits;
   });
 
@@ -368,6 +419,28 @@ export default function SessionView(props: SessionViewProps) {
   });
 
   const searchActive = createMemo(() => searchOpen() && searchQuery().trim().length > 0);
+  const totalPartCount = createMemo(() => props.messages.reduce((total, message) => total + message.parts.length, 0));
+
+  const computeWindowStart = (messages: MessageWithParts[]) => {
+    const total = messages.length;
+    if (!total) return 0;
+
+    let count = 0;
+    let parts = 0;
+
+    for (let index = total - 1; index >= 0; index -= 1) {
+      const nextCount = count + 1;
+      const nextParts = parts + (messages[index]?.parts.length ?? 0);
+      if (nextCount > INITIAL_MESSAGE_WINDOW || nextParts > INITIAL_PART_WINDOW) {
+        return Math.min(total - 1, index + 1);
+      }
+      count = nextCount;
+      parts = nextParts;
+    }
+
+    return 0;
+  };
+
   const renderedMessages = createMemo(() => {
     if (messageWindowExpanded() || searchActive()) return props.messages;
 
@@ -393,12 +466,50 @@ export default function SessionView(props: SessionViewProps) {
     const hidden = hiddenMessageCount();
     if (hidden <= 0) return;
     const nextStart = Math.max(0, messageWindowStart() - MESSAGE_WINDOW_LOAD_CHUNK);
+    if (props.developerMode) {
+      recordPerfLog(true, "session.window", "reveal", {
+        sessionID: props.selectedSessionId,
+        hiddenBefore: hidden,
+        nextStart,
+      });
+    }
     setMessageWindowStart(nextStart);
     if (nextStart === 0) {
       setMessageWindowExpanded(true);
     }
   };
 
+  let lastWindowPerfSignature = "";
+  createEffect(() => {
+    if (!props.developerMode) {
+      lastWindowPerfSignature = "";
+      return;
+    }
+
+    const signature = [
+      props.selectedSessionId ?? "",
+      props.messages.length,
+      totalPartCount(),
+      renderedMessages().length,
+      hiddenMessageCount(),
+      messageWindowExpanded() ? "1" : "0",
+      searchActive() ? "1" : "0",
+    ].join("|");
+
+    if (signature === lastWindowPerfSignature) return;
+    lastWindowPerfSignature = signature;
+
+    recordPerfLog(true, "session.window", "state", {
+      sessionID: props.selectedSessionId,
+      messageCount: props.messages.length,
+      renderedMessageCount: renderedMessages().length,
+      hiddenMessageCount: hiddenMessageCount(),
+      partCount: totalPartCount(),
+      expanded: messageWindowExpanded(),
+      searchActive: searchActive(),
+    });
+  });
+
   const canUndoLastMessage = createMemo(() => {
     if (!props.selectedSessionId) return false;
     const revert = props.sessionRevertMessageId;
@@ -412,11 +523,17 @@ export default function SessionView(props: SessionViewProps) {
     return false;
   });
 
+  const hasUserMessages = createMemo(() =>
+    props.messages.some((message) => (message.info as { role?: string }).role === "user"),
+  );
+
   const canRedoLastMessage = createMemo(() => {
     if (!props.selectedSessionId) return false;
     return Boolean(props.sessionRevertMessageId);
   });
 
+  const canCompactSession = createMemo(() => Boolean(props.selectedSessionId) && hasUserMessages());
+
   const touchedFiles = createMemo(() => {
     const out: string[] = [];
     const seen = new Set<string>();
@@ -633,7 +750,7 @@ export default function SessionView(props: SessionViewProps) {
 
   createEffect(
     on(
-      () => [props.selectedSessionId, props.messages.length] as const,
+      () => [props.selectedSessionId, props.messages.length, totalPartCount()] as const,
       ([sessionId, count], previous) => {
         const previousSessionId = previous?.[0] ?? null;
         if (sessionId !== previousSessionId) {
@@ -646,7 +763,7 @@ export default function SessionView(props: SessionViewProps) {
         if (messageWindowExpanded()) return;
         if (count === 0) return;
 
-        const targetStart = count > INITIAL_MESSAGE_WINDOW ? count - INITIAL_MESSAGE_WINDOW : 0;
+        const targetStart = computeWindowStart(props.messages);
         if (messageWindowSessionId() !== sessionId) {
           setMessageWindowStart(targetStart);
           setMessageWindowSessionId(sessionId);
@@ -980,6 +1097,7 @@ export default function SessionView(props: SessionViewProps) {
       () => {
         setSearchOpen(false);
         setSearchQuery("");
+        setSearchQueryDebounced("");
         setActiveSearchHitIndex(0);
       },
     ),
@@ -1068,7 +1186,7 @@ export default function SessionView(props: SessionViewProps) {
       () => [
         props.messages.length,
         props.todos.length,
-        props.messages.reduce((acc, m) => acc + m.parts.length, 0),
+        totalPartCount(),
       ],
       (current, previous) => {
         if (!previous) return;
@@ -1182,6 +1300,7 @@ export default function SessionView(props: SessionViewProps) {
 
   const closeSearch = () => {
     setSearchOpen(false);
+    setSearchQueryDebounced("");
   };
 
   const moveSearchHit = (offset: number) => {
@@ -1231,6 +1350,35 @@ export default function SessionView(props: SessionViewProps) {
     }
   };
 
+  const compactSessionHistory = async () => {
+    if (historyActionBusy()) return;
+    if (!canCompactSession()) {
+      setToastMessage("Nothing to compact yet.");
+      return;
+    }
+
+    const sessionID = props.selectedSessionId;
+    const startedAt = perfNow();
+    setHistoryActionBusy("compact");
+    setToastMessage("Compacting session context...");
+    try {
+      await props.compactSession();
+      setToastMessage("Session compacted.");
+      finishPerf(props.developerMode, "session.compact", "ui-done", startedAt, {
+        sessionID,
+      });
+    } catch (error) {
+      const message = error instanceof Error ? error.message : props.safeStringify(error);
+      setToastMessage(message || "Failed to compact session");
+      finishPerf(props.developerMode, "session.compact", "ui-error", startedAt, {
+        sessionID,
+        error: message,
+      });
+    } finally {
+      setHistoryActionBusy(null);
+    }
+  };
+
 
   const triggerFlyout = (
     sourceEl: Element | null,
@@ -2318,6 +2466,18 @@ export default function SessionView(props: SessionViewProps) {
                 <Loader2 size={16} class="animate-spin" />
               </Show>
             </button>
+            <button
+              type="button"
+              class="h-9 w-9 flex items-center justify-center rounded-lg text-dls-secondary hover:text-dls-text hover:bg-dls-hover transition-colors disabled:opacity-60 disabled:cursor-not-allowed"
+              onClick={compactSessionHistory}
+              disabled={!canCompactSession() || historyActionBusy() !== null}
+              title="Compact session context"
+              aria-label="Compact session context"
+            >
+              <Show when={historyActionBusy() === "compact"} fallback={<Maximize2 size={16} />}>
+                <Loader2 size={16} class="animate-spin" />
+              </Show>
+            </button>
             <div ref={(el) => (sessionMenuRef = el)} class="relative">
               <button
                 type="button"
@@ -2336,9 +2496,20 @@ export default function SessionView(props: SessionViewProps) {
 
               <Show when={sessionMenuOpen() && props.selectedSessionId}>
                 <div
-                  class="absolute right-0 top-[calc(100%+4px)] z-20 w-44 rounded-lg border border-dls-border bg-dls-surface shadow-lg p-1"
+                  class="absolute right-0 top-[calc(100%+4px)] z-20 w-52 rounded-lg border border-dls-border bg-dls-surface shadow-lg p-1"
                   onClick={(event) => event.stopPropagation()}
                 >
+                  <button
+                    type="button"
+                    class="w-full text-left px-2 py-1.5 text-sm rounded-md hover:bg-dls-hover disabled:opacity-60"
+                    onClick={() => {
+                      setSessionMenuOpen(false);
+                      void compactSessionHistory();
+                    }}
+                    disabled={!canCompactSession() || historyActionBusy() !== null}
+                  >
+                    Compact session context
+                  </button>
                   <button
                     type="button"
                     class="w-full text-left px-2 py-1.5 text-sm rounded-md hover:bg-dls-hover"